1. Field of the Invention
This invention relates generally to the field of ATM network analysis. More particularly, this invention relates to the field of automatic connection identification and analysis in an ATM network.
2. Description of Background Art
In recent years, there has been a sharp increase in the demand for network bandwidth which has been principally driven by two trends: (i) the increasing number of networked computers exchanging data; and (ii) the increasing need for networked computers to exchange ever-increasing quantities of data. In response to this demand, a variety of new computer network technologies have been developed that improve upon existing technologies by increasing the efficiency of data transmission, increasing the speed of data transmission, or both. One network technology incorporating both improvements is the asynchronous transfer mode (ATM) network. Although these new technologies achieve increased network bandwidth, they also create a need for new and improved technologies to analyze networks incorporating these technologies
The prevailing network topology of earlier generations of networks, such as Ethernet, Token Ring, and fiber distributed data interface (FDDI), is one of a shared physical link. All of such network's end stations are attached to the same network segment or link and share a single physical link having a fixed bandwidth. Such networks are referred to as broadcast networks since the data transmitted from a single station may be received by all other stations on that link. One disadvantage of broadcast networks is that the addition of more end stations onto the link reduces the average bandwidth available to each station on that link. However, analyzing network traffic on a broadcast network is relatively straightforward since the single shared bandwidth link may be monitored at any point to receive all traffic that flows through that link.
As the demand for network bandwidth increased, new solutions were developed to overcome the shortcomings of shared bandwidth. One technology developed to improve network efficiency is commonly known in the art as switched networking or microsegmentation. Switched networks improve network bandwidth by establishing a dedicated link between an end station and a port on a network switch. The network switch routes all traffic in such a network by directing the traffic only to the stations that are the traffic's destination. In doing so, no broadcasting occurs as in the shared link approach and the link's full bandwidth is always available whenever the switch or end station seeks to transmit. Although switching improves a network's efficiency, the inability for all end stations to listen to the traffic sent to other stations in the same segment makes the task of analyzing, i.e., monitoring, network traffic more difficult since one must develop a method to monitor the traffic on multiple links simultaneously.
Additional improvements were made to switched networks to further improve bandwidth. ATM networks improve upon the switched network model by introducing virtual circuits and intelligent switching. Virtual circuit bandwidth allocation and transfer characteristics, such as delays and delay variations, can be tailored to the application traffic's needs. End stations can now request, through intelligence in the switches and signaling protocols, that the network provide the necessary bandwidth and quality of services needed on each virtual circuit. Primarily as a result of those improvements, ATM networks can simultaneously transport multiple types of network traffic, such as voice, data, and video, on a single physical link using different service types based upon the requirements of the traffic. However, analysis of the traffic on an ATM network is difficult because each such service type utilizes a different data container.
The improvements of virtual circuits permit increased bandwidth utilization in an ATM network However this increased bandwidth utilization also increases the complexity of the ATM network. A single physical link is subdivided into virtual paths (VP), which are further subdivided into virtual channels (VC). Currently, typical ATM networks permit subdivision of a physical link into a maximum of approximately four thousand VP's, and the VP's may be further subdivided into a maximum of approximately sixty-four thousand VC's. Thus, there are potentially in excess of 256 million (2.sup.28) assignable virtual circuits within each dedicated link. Despite the large number of potential virtual circuits, frequently, the number of ATM virtual circuits (VP/VC pairs, channels) that are of interest to the user of a network analysis device is significantly less than the total number of potential ATM channels.
Each virtual circuit may be identified by its associated VP/VC pair. For example, if the VP is 3 and the VC is 42, the channel can be denoted as 3/42. With the exception of special use channels, for example, the first thirty-two VC's associated with VP 0 (which are reserved for specific functions, such as 0/5 for signaling and 0/16 for interim local management interface), most of the other ATM network channels may potentially be an active virtual channel.
Prior to the widespread availability of signaling capability in ATM systems, all channel assignments were accomplished by the use of permanent virtual circuits (PVCs). PVC's are configured on a channel-by-channel basis by a manual assignment process occurring at both the ATM switch console and ATM end stations. Typically, such PVC's are left unchanged, i.e., permanently setup, until the channel is no longer needed. Additional ATM network technology improvements now permit the end stations themselves to transmit a signal request to the appropriate network device to request that a virtual circuit be set-up, connected, or released as needed. Such virtual circuits are known as switched virtual circuits (SVCs). In a network supporting SVC's, the virtual circuit setup and release requests are transmitted in a signaling channel, typically assigned to channel 0/5.
The analysis of ATM network traffic is made difficult by the large number of potentially active virtual circuits and the ability for virtual circuits to be created and disconnected in a manner which is transparent to a user. Currently, in order to analyze an ATM network, an ATM network device, must already know the active channels. There is a need for a method and system to connect a network analysis device to an already active ATM network and: (i) automatically identify all active ATM network channels, even those active channels established prior to the connection of the ATM network analysis device to the ATM network; (ii) automatically track status changes to the active channels; and (iii) identify the quality of service utilized by the active channels.
In addition to the implementation of virtual circuits, ATM networks also typically operate over a wider and higher range of speed than other network topologies, with the common current rates of data transfer on ATM networks being 155 Mbps and 622 Mbps. Typical network analysis devices capture all network traffic in high speed capture buffers. However, due to the increased data flow of an ATM network, typical implementations of high speed capture buffers for an ATM network analysis device may be insufficient. Unless the buffers are very large, high speed data capture buffers will overflow and network data may be lost. To reduce the necessary size of the capture buffers and to reduce the need for new processors or processing approaches to analyze the high speed ATM network traffic, a filtering technique is needed to efficiently select network data that should be further analyzed.
What is needed is a system and method for connecting a network analysis device to an ATM network to: (i) automatically identify all active ATM network channels, even those active channels established prior to the connection of the ATM network analysis device to the ATM network; (ii) automatically track status changes to the active channels; (iii) identify the service parameters utilized by the active channels; and (iv) filter the detected data and to capture and store only the data of interest, e.g., only data sent from a particular station.